Algebra 1 Common Core Student Edition, Grade 8-9

Points

Object ive To find mean, median, mode, and range

Get t in g Read y!

What criteria are

you going t o use t o

make your choice?

V

MATHEMATICAL

PRA CTI CES

Ref er t o t h e d at a at t h e r ig h t.

Which basketball player would you

rat h er have on your t eam? Ju st i f y

your answer.

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Lesso n i
Vocabulary
measure of
central tendency

• o u tlie r


• mean


• median
  
  
  • m ode
  
  
  • m easure o f
    dispersion
  
  
  • r a n g e o f a se t o f
    data
  
  
  
  

Essent ial Und er st and ing You can use different measures to interpret and

compare sets of data.

One way to summarize a set of data is to use a measure of central tendency. Mean,

median, and mode are all measures of central tendency.

The measure of central tendency that best describes a data set may depend on whether

the data set has an outlier. An outlier is a data value that is much greater or less than the

other values in the set. Below is a review of mean, median, and mode, and when to use

each as the measure of central tendency.

Key Concept Mean, Median, and Mode

Measure

n, The mean equals tota] number of data values. The mean, sum of the data values ...

is often referred to as the average.

When to Use

Use mean to describe the middle of a

set of data that does not have an outlier.

The median is the middle value in a data set

when the values are arranged in order. For a set

containing an even number of data values, the

median is the mean of the two middle data values.

Use median to describe the middle of

a set of data that does have an outlier.

The mode is the data item that occurs the most

times. A data set can have no mode, one mode, or

more than one mode.

Use mode when the data are

nonnumeric or when choosing the

most popular item.

Common Core State Standards

Ten d en cy an d D i sp er si o n

l 1 n c 1. I S-ID.A.2 Use st at ist ics ap p ro p riat e t o t he... dat a

/V V G Q SUi SS O l V^ SllTrQ I distribution to compare center... and spread...

of two or more different data sets. Also S-ID.A.3,

N-Q.A.2

MP 1, MP 2, MP 3, MP 4, MP 6

738 Chapter 12 Dat a A n al ysi s an d Pr o b ab i li t y